Development and validation of a fluorescence method to follow the build-up of short peptide sequences on solid 2D surfaces

The modification of material surfaces with short peptide sequences has become an essential step in many biotechnological and biomedical applications. Due to their simple architecture compared to more complex 3D substrates, 2D surfaces are of particular interest for high throughput applications and as model surfaces for dynamic or responsive surface modifications. The decoration of these surfaces with peptides is commonly accomplished by synthesizing the peptide first and subsequently transferring it onto the surface of the substrate. Recently, several procedures have been described for the synthesis of peptides directly onto a 2D surface, thereby simplifying and accelerating the modification of flat surfaces with peptides. However, the wider use of these techniques requires a routine method to monitor the amino acid build-up on the surface. Here, we describe a fast, inexpensive and nondestructive fluorescence based method which is readily accessible to follow the amino acid build-up on solid 2D samples.     

Energy Scales in the High-Tc Superconductor YBa2Cu3O6+x

The optical conductivity sum rule is used to examine the evolution of the spectral weight N() in both the normal and superconducting states of optimally and underdoped YBa₂Cu₃O_6+x along the a axis. Differences in N() above and below T _c allow the strength of the superconducting condensate _s to be determined. In the optimally-doped material, _s is fully formed at energies comparable to the full superconducting gap maximum (0.1 eV), while in the underdoped material the energy scale for convergence is considerably higher (0.6 eV). This difference is discussed in terms of normal-state properties.     

Near infrared spectroscopy patents for the physicochemical characterization of nanomaterials: the road from production to routine high-throughput quality control

The measurement of the physical and chemical ("physicochemical") properties of nanomaterials used in industry and science including chemistry, pharmacy, medicine, toxicology, etc., is time-consuming, expensive and requires a lot of experience of a well trained lab staff. Near-infrared spectroscopy (NIR; 4.000-12.000 cm(-1)), working in the wavelength region with the highest IR energy, allows obtaining multifactorial information of the material under investigation due to the occurrence of a high number of combination and overtone vibrations. Coupling of an optimized and well-designed measurement technique with multivariate data analysis (MVA) leads to a non-destructive, fast, reliable and robust novel NIR technique for the fast and non-invasive physicochemical characterization, which is suitable for high-throughput quality control due to the short analyses times of only a few seconds. In the following chapters, the patented basic NIR techniques full-filling these aims are introduced, described, summarized and critically discussed.     

Interfacial Approach toward Benzene‐Bridged Polypyrrole Film–Based Micro‐Supercapacitors with Ultrahigh Volumetric Power Density

2D soft nanomaterials are an emerging research field due to their versatile chemical structures, easily tunable properties, and broad application potential. In this study, a benzene‐bridged polypyrrole film with a large area, up to a few square centimeters, is synthesized through an interfacial polymerization approach. As‐prepared semiconductive films exhibit a bandgap of ≈2 eV and a carrier mobility of ≈1.5 cm² V^?1 s^?1, inferred from time‐resolved terahertz spectroscopy. The samples are employed to fabricate in‐plane micro‐supercapacitors (MSCs) by laser scribing and exhibit an ultrahigh areal capacitance of 0.95 mF cm^?2, using 1‐ethyl‐3‐methylimidazolium tetrafluoroborate ([EMIM][BF₄]) as an electrolyte. Importantly, the maximum energy and power densities of the developed MSCs reach values up to 50.7 mWh cm^?3 and 9.6 kW cm^?3, respectively; the performance surpassing most of the 2D material‐based MSCs is reported to date.     

Transient Gratings Formed by Nonequilibrium Quasiparticles in YBa2Cu3O6.5

We report transient grating measurements of nonequilibrium quasiparticles in untwinned single crystals of YBa₂Cu₃O_6.5. By interfering two laser beams on the sample, we introduce a sinusoidally varying density of nonequilibrium quasiparticles. A third laser beam incident on this pattern is both reflected and diffracted due to the sinusoidally varying index change caused by photoinduced quasiparticles. In this paper, we focus on the low excitation density limit. In this limit, measuring the reflected and diffracted beams as a function of the time and grating period yields the diffusion constant and elastic scattering rate for these nonequilibrium quasiparticles.     

Local field effects on electron transport in nanostructured TiO2 revealed by terahertz spectroscopy

We study electron mobilities in nanoporous and single-crystal titanium dioxide with terahertz time domain spectroscopy. This ultrafast technique allows the determination of the electron mobility after carrier thermalization with the lattice but before equilibration with defect trapping states. The mobilities reported here for single-crystal rutile (1 cm2/(V s)) and porous TiO2 (10(-2) cm2/(V s)) therefore represent upper limits for electron transport at room temperature for defect-free materials. The large difference in mobility between bulk and porous samples is explained using Maxwell-Garnett effective medium theory. These results demonstrate that electron mobility is strongly dependent on the material morphology in nanostructured polar materials due to local field effects and cannot be used as a direct measure of the diffusion coefficient.     

Size-dependent electron transfer from PbSe quantum dots to SnO2 monitored by picosecond Terahertz spectroscopy

We report the direct and unambiguous determination of electron transfer rates and efficiencies from PbSe quantum dots (QDs) to mesoporous SnO2 films. We monitor the time-dependent electron density within the oxide with picosecond time resolution using Terahertz spectroscopy, following optical excitation of the QDs using a femtosecond laser pulse. QD-oxide electron transfer occurs with efficiencies of ～2% in our samples under 800 nm pumping with a marked dependence on QD size, ranging from ～100 ps injection times for the smallest, ～2 nm diameter QDs, to ～1 ns time scale for ～7 nm QDs. The size-dependent electron transfer rates are modeled within the framework of Marcus theory and the implications of the results for device design are discussed.